1. Field of the Invention
This invention relates to a dumping work determination system for a haulage vehicle. The dumping work determination system performs a determination as to the state of loading in a vessel in dumping work from the haulage vehicle.
2. Description of the Related Art
In general, a large haulage vehicle such as a dump truck is provided with a vessel raisably disposed on a body frame. The haulage vehicle travels with a payload (for example, crushed stone or earth) loaded in a large quantity in the vessel, whereby the haulage of the payload is performed. As one of the conventional art on such haulage vehicles, there is known a haulage vehicle provided with hoist cylinders, a hydraulic power source, a control valve unit, and a control device (see, for example, JP-A-2013-28306). The hoist cylinders are telescopically disposed between a vessel and a body frame such that, when dumping a payload from the vessel, the hoist cylinders extend to obliquely tilt the vessel. The hydraulic power source produces pressure oil to be supplied to the hoist cylinders. The control valve unit is disposed between the hydraulic power source and the hoist cylinders to control the supply and drainage of pressure oil to and from the hoist cylinders. The control device performs switching control of the control valve unit.
After traveling, with a payload loaded in the vessel, to a dumping site at a delivery destination, the haulage vehicle of this conventional technology extends the hoist cylinders to lift up the vessel obliquely rearward so that the payload is dumped to the dumping site along the direction of an inclination of the vessel. If the payload in the vessel is a high-stickiness payload, for example, like clayish earth, some of the payload may stick an inner side of the vessel and may not slide down even when the vessel is tilted toward the rear of the body frame.
To prevent the payload from remaining in the vessel as mentioned above, the haulage vehicle of the conventional technology is configured to control the switching of the control valve unit such that upon performing the dump work of the payload, in other words, dumping work, the hoist cylinders are allowed to shake up and down in its extension/contraction direction.